Domain growth, budding, and fission in phase-separating self-assembled fluid bilayers

Area of Science:

• Soft Matter Physics
• Biophysics
• Computational Chemistry

Background:

• Understanding phase separation in lipid membranes is crucial for cell biology and materials science.
• Previous studies often simplified or neglected the roles of hydrodynamics and area-to-volume constraints.

Purpose of the Study:

• To systematically investigate phase-separation dynamics in binary fluid vesicles and open membranes.
• To elucidate the impact of hydrodynamics and area-to-volume constraints on these dynamics.

Main Methods:

• Employed large-scale dissipative particle dynamics (DPD) simulations.
• Explicitly included solvent effects to capture hydrodynamic interactions.
• Analyzed systems with both asymmetric and symmetric lipid compositions.

Main Results:

• Observed distinct regimes in asymmetric mixtures: flat patch coalescence, budding, vesiculation, and cap coalescence.
• Demonstrated significant influence of area-to-volume constraints and hydrodynamics on these regimes and transitions.
• Identified a universal growth regime with a 1/2 exponent for symmetric mixtures, independent of area-to-volume ratio, also seen in open membranes.

Conclusions:

• Hydrodynamics and area-to-volume constraints are critical factors governing phase separation in complex lipid systems.
• A universal growth exponent of 1/2 characterizes symmetric mixture phase separation in vesicles and open membranes.
• DPD simulations provide a powerful tool for studying fluid membrane dynamics under realistic physical constraints.